Weegy: 6.
the factors of 12 are 2x2x3
the factors of 54 are 2x3x3x3
because you have 2x3 in both the first and the second one, you can determine that 6 goes into both 12 and 54. [ (it's the GCF) =) http:// /question/?qid=20071105171616AAwD6fW ]